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| 42. |
- Karlsson, Ida K., et al.
(författare)
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Measuring heritable contributions to Alzheimer's disease : polygenic risk score analysis with twins
- 2022
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Ingår i: Brain Communications. - : Oxford University Press. - 2632-1297. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- The heritability of Alzheimer's disease estimated from twin studies is greater than the heritability derived from genome-based studies, for reasons that remain unclear. We apply both approaches to the same twin sample, considering both Alzheimer's disease polygenic risk scores and heritability from twin models, to provide insight into the role of measured genetic variants and to quantify uncaptured genetic risk. A population-based heritability and polygenic association study of Alzheimer's disease was conducted between 1986 and 2016 and is the first study to incorporate polygenic risk scores into biometrical twin models of Alzheimer's disease. The sample included 1586 twins drawn from the Swedish Twin Registry which were nested within 1137 twin pairs (449 complete pairs and 688 incomplete pairs) with clinically based diagnoses and registry follow-up (M-age = 85.28, SD = 7.02; 44% male; 431 cases and 1155 controls). We report contributions of polygenic risk scores at P < 1 x 10(-5), considering a full polygenic risk score (PRS), PRS without the APOE region (PRS.no.APOE) and PRS.no.APOE plus directly measured APOE alleles. Biometric twin models estimated the contribution of environmental influences and measured (PRS) and unmeasured genes to Alzheimer's disease risk. The full PRS and PRS.no.APOE contributed 10.1 and 2.4% to Alzheimer's disease risk, respectively. When APOE e4 alleles were added to the model with the PRS.no.APOE, the total contribution was 11.4% to Alzheimer's disease risk, where APOE e4 explained 9.3% and PRS.no.APOE dropped from 2.4 to 2.1%. The total genetic contribution to Alzheimer's disease risk, measured and unmeasured, was 71% while environmental influences unique to each twin accounted for 29% of the risk. The APOE region accounts for much of the measurable genetic contribution to Alzheimer's disease, with a smaller contribution from other measured polygenic influences. Importantly, substantial background genetic influences remain to be understood. Karlsson et al. report that measured polygenic scores from genome-based studies, including an outsized role for APOE, explain only a fraction of the heritability indicated by twin models of Alzheimer's disease, leaving most genetic risk for Alzheimer's disease unexplained. Sensitive designs are needed to capture all the genetic influences.
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| 43. |
- Karlsson, Ida K., et al.
(författare)
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The dynamic association between body mass index and cognition from midlife through late-life, and the effect of sex and genetic influences
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Body mass index (BMI) is associated with cognitive abilities, but the nature of the relationship remains largely unexplored. We aimed to investigate the bidirectional relationship from midlife through late-life, while considering sex differences and genetic predisposition to higher BMI. We used data from 23,892 individuals of European ancestry from the Health and Retirement Study, with longitudinal data on BMI and three established cognitive indices: mental status, episodic memory, and their sum, called total cognition. To investigate the dynamic relationship between BMI and cognitive abilities, we applied dual change score models of change from age 50 through 89, with a breakpoint at age 65 or 70. Models were further stratified by sex and genetic predisposition to higher BMI using tertiles of a polygenic score for BMI (PGSBMI). We demonstrated bidirectional effects between BMI and all three cognitive indices, with higher BMI contributing to steeper decline in cognitive abilities in both midlife and late-life, and higher cognitive abilities contributing to less decline in BMI in late-life. The effects of BMI on change in cognitive abilities were more evident in men compared to women, and among those in the lowest tertile of the PGSBMI compared to those in the highest tertile, while the effects of cognition on BMI were similar across groups. In conclusion, these findings highlight a reciprocal relationship between BMI and cognitive abilities, indicating that the negative effects of a higher BMI persist from midlife through late-life, and that weight-loss in late-life may be driven by cognitive decline.
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| 44. |
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| 45. |
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| 46. |
- Kåreholt, Ingemar, et al.
(författare)
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Baseline leisure time activity and cognition more than two decades later
- 2011
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Ingår i: International Journal of Geriatric Psychiatry. - : Wiley. - 0885-6230 .- 1099-1166. ; 26:1, s. 65-74
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Many studies of the relation between factors earlier in life and late-life cognition have a short follow-up time, often less than 10 years. Since cognitive decline can be present up to 20 years prior to dementia it is difficult to distinguish the direction of the relationships without a long follow-up. We analyzed the association between different types of leisure time activity at baseline and cognition more than 20 years later. A wide range of activities was included—political, mental, socio-cultural, social, physical, and organizational activities.Methods: Baseline studies were random Swedish samples aged 46–75 years (mean 57.4) (n = 1643) interviewed in 1968 or 1981. Activities were measured at baseline. Cognition was measured with items from the Mini-Mental State Examination in 1992, 2002, or 2004.Results: There was a significant association between later cognition and earlier political, mental, and socio-cultural activities controlling for age, age-square, sex, follow-up-time, mobility problems, symptoms of mental distress, employment status, education, adult and childhood socioeconomic status, income, smoking, and drinking. Physical activities had a significant association with cognition only among women. Organizational activities were not significant when controlling for all covariates. Social activities had no significant association. Including all covariates and all leisure activities simultaneously, only mid-life political and mental activities remained significantly related to later life cognition.Conclusions: These findings add support to the theory that various forms of engagement in mid-life can have a protective effect with respect to cognition in later life.
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| 47. |
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| 48. |
- Luo, Jing, et al.
(författare)
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Dementia risk in women higher in same-sex than opposite-sex twins
- 2020
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Ingår i: Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring. - : John Wiley & Sons. - 2352-8729. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionHormones may be one possible mechanism underlying sex differences in dementia incidence. We examined whether presumed differential prenatal hormone milieu is related to dementia risk by comparing dementia rates in same- and opposite-sex dizygotic twin pairs in male and female twins.MethodsThe sample comprised 43,254 individuals from dizygotic twin pairs aged 60 and older from the Swedish Twin Registry. Survival analyses were conducted separately for females and males.ResultsFemale twins from opposite-sex pairs had significantly lower dementia risk than female twins from same-sex pairs, but the differences emerged only after age 70 (hazard ratio = 0.64, P = 0.004). Results were not explained by postnatal risk factors for dementia, and no interaction between twin type and apolipoprotein E (APOE) epsilon 4 was found. Male twins from same-sex versus opposite-sex pairs did not differ significantly.DiscussionThe results suggest that relatively masculine prenatal hormone milieus correlate with lower dementia risk in females.
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| 49. |
- Pahlen, Shandell, et al.
(författare)
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Age-moderation of genetic and environmental contributions to cognitive functioning in mid- and late-life for specific cognitive abilities
- 2018
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Ingår i: Intelligence. - : Elsevier. - 0160-2896 .- 1873-7935. ; 68, s. 70-81
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Tidskriftsartikel (refereegranskat)abstract
- Age moderation of genetic and environmental contributions to Digits Forward, Digits Backward, Block Design, Symbol Digit, Vocabulary, and Synonyms was investigated in a sample of 14,534 twins aged 26 to 98 years. The Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium contributed the sample, which represents nine studies from three countries (USA, Denmark, and Sweden). Average test performance was lower in successively older age groups for all tests. Significant age moderation of additive genetic, shared environmental, and non-shared environmental variance components was observed, but the pattern varied by test. The genetic contribution to phenotypic variance across age was smaller for both Digit Span tests, greater for Synonyms, and stable for Block Design and Symbol Digit. The non-shared environmental contribution was greater with age for the Digit Span tests and Block Design, while the shared environmental component was small for all tests, often more so with age. Vocabulary showed similar age-moderation patterns as Synonyms, but these effects were nonsignificant. Findings are discussed in the context of theories of cognitive aging.
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